Sutures having fixed points of attachment to tissue, such as retainers (or “barbs”), do not typically enable tissue to stretch. Such self-retaining sutures are secured into the tissue by embedding the retainers into a portion of the tissue, thereby holding the suture along its barbed length securely in tissue. While this may be acceptable for many surgical applications, as the retainers maintain the suture in its implanted position without the need for additional anchors, it may not be preferable for certain applications. In some procedures, the implanted suture could benefit from the ability to stretch along the length of the suture. Such procedures include, for example, those used to retain surgical mesh in place, suturing of sphincters or other bodily orifices that functionally expand and contract, and in applications where the sutured tissue is expected to grow (e.g., when used in patients who are not fully grown).
While self-retaining sutures themselves are known, present sutures are limited. The main application for sutures, such as barbed sutures, currently is to approximate and close tissue gaps, where the gap is intended to remain closed and there is little desire to stretch and move. This is the precise reason that many self-retaining sutures are not intended to “give” under low stresses (such as less than about 0.5 lb). If the suture does give under this level of stress, it would be considered by many to be a failure and may not achieve its intended purpose. This is especially true when used in closing a surgical wound for healing. Although there are various designs known, none has demonstrated the ability to elongate at a significant displacement (greater than 5 mm) under non-catastrophic stresses and return to its original state when stresses are removed. There is a need for sutures, including self-retaining sutures, to allow for stretching and flexibility after implantation.